All Subjects will receive AGS-8M4 treatment. Subjects will be enrolled into 1 of 2 treatment arms according to their disease status. A disease assessment will be performed every 8 or 9 weeks (± 3 days) depending on the treatment arm assignment. The assessment will be based both on changes in clinical symptoms, and radiographic images. Subjects without evidence of disease progression may continue to receive treatment based on their original treatment assignment until disease progression or intolerability. A safety follow-up visit will occur 4 weeks after the last dose infusion of AGS-8M4.